The present invention relates to a new type of shell intended to increase mainly the effective range of anti-aircraft cannon, in the case of all near misses, to the greatest possible extent by concentrating the fragments formed on detonation of the shell in the direction of the target. The invention involves more specifically a combination of a specially designed explosive-charged shell forming fragments on its detonation and a special type of proximity fuse intended to initiate the explosive charge when a target is detected. The detailed construction of the proximity fuse has nothing to do with the invention, however, the fact that it is available is a prerequisite for the invention. The purpose of the invention is therefore partly to increase the potential of the AA artillery for combating extremely difficult targets such as sea-skimmers etc. and partly to increase the effect of the individual shells on more conventional targets. Also, the purpose is to reduce the dependency of anti-aircraft cannon on entirely accurate range calculations which, in spite of the most modern technology available, can be difficult to achieve in the rapid combat sequences which are now involved in combating air targets. Furthermore the number of targets which are extremely difficult to combat in the form of autonomous guided or self-guiding weapon carriers with small external dimensions can be expected to increase in the future since the air force seeks to an ever increasing extent to be able to combat a selected target without having itself to enter the risk area around the target.
Naval and field barrel-type anti-aircraft weapons of today consist mainly of automatic cannons of 20-76 mm caliber and for these use is as a rule made of explosive-charged high-explosive shells or ball-type high-explosive shells which, at least in the larger 40-76 mm calibers, are usually equipped with proximity fuses for initiation in the case of near misses of the target. For direct hits on the target there are percussion initiation functions.
The generation of proximity fuses in general use today have an antenna pattern with relatively undefined omnidirectional seeking beams, and in the same way the fragments formed on the detonation of the high-explosive shells and ball-type high-explosive shells of today are scattered radially from them about their own longitudinal axis.
The advantage of a combination of the omnidirectional proximity fuse and the omnidirectional fragmentation shell is that, with this combination, there is no need to keep track of the rotational position of the shell which therefore simplifies the initiation system. It is therefore only necessary for the proximity fuse to have ascertained that the shell is sufficiently close to a target for initiation of the explosive to take place. The disadvantage, however, is that the energy of the explosive charge and of the fragments scattered on its detonation is scattered while turning and is therefore directed only to a limited extent towards the target. For a single 40 mm AA shell, this means that it must today be as close to the target as roughly 5 meters in order to ensure that the target is shot down. Considering the rapid targets of today, it will be absolutely clear that such a close hit picture requires extraordinarily accurate prediction.